Advances in the criteria for dividing thin superconducting films into narrow and wide films

TL;DR

This paper investigates the critical currents and nonequilibrium phenomena in thin Sn superconducting films, revealing that the traditional criterion for dividing narrow and wide films based on the width-to-penetration-depth ratio is insufficient.

Contribution

It introduces a new understanding of the transition between narrow and wide superconducting films, challenging the conventional w ~ lambda criterion.

Findings

The transition to a wide-film regime occurs only for w/lambda(T) > 10-20.

A wide transitional region exists where w > lambda but the behavior does not align with existing vortex state theory.

The traditional criterion w ~ lambda is inadequate for classifying thin superconducting films.

Abstract

The results of experimental investigations of the critical currents and certain nonequilibrium phenomena in thin Sn films of different width w are analyzed. Usually, thin superconducting films are divided into two groups: narrow channels w<lambda and wide films w>lambda. A wide transitional region where the condition w>lambda holds with a large margin and at the same time cannot be explained from the standpoint of the theory of the appearance of a vortex state has been found. This shows that the generally accepted criterion w \sim lambda for dividing films into wide and narrow does not work. The transition into a wide-film regime, described by the existing theory of the vortex state, is fully completed only for w/lambda(T) > 10-20.